EEG

Electroencephalography (EEG) recordings are of important added value in quantifying the effects of drugs targeting the central nervous system (CNS). CHDR has extensive experience in performing EEG recordings and analysis for research purposes in a wide range of neurological and psychiatric conditions.

Resting state EEG

Resting-state EEG is very sensitive to the effects of pharmacological substances on the brain. For this reason, pharmaco-EEG has become an established method for assessing drug effects on central nervous system (CNS) functioning. Examples of drug effects that can be detected with resting-state EEG include increases in the power of the β and γ bands and decreases in the power of α frequencies in response to benzodiazepine treatment, and increases in the power of the δ and θ bands during anaesthesia or following administration of 5-HT2 receptor antagonists.

Stimulus-related and task-related EEG

EEG recordings enable us to quantify the functional integrity of different brain areas. CHDR offers the possibility to read out a wide range of stimulus-related and task-related neurophysiological responses, including:

Endogenous Event-Related Potential (ERP) P300 to reflect processes involved in stimulus evaluation or categorization
ERPs P50 and N100 to capture sensory gating, the process by which repetitive, redundant information is filtered to prevent flooding of the cortex with irrelevant information
Mismatch Negativity to explore information processing in the healthy brain
Auditory Steady-State Response (ASSR) testing to assess the brain's electrical response to auditory stimuli
Visual Evoked Potentials (VEPs) to quantify the functional integrity of the visual cortex
Laser Evoked Potentials (LEPs) to investigate the peripheral and central processing of nociceptive inputs
Potentials evoked by Transcranial Magnetic Stimulation (TMS) to clinically study the effects of drugs that are expected to affect nerve or corticospinal excitability
Potentials evoked by Intraepidermal Electrical Stimuli (IES) to reflect the central sensitisation of nociceptive pathways

Intermittent photic stimulation (IPS)

We offer Intermittent Photic Stimulation (IPS) as a method to identify photoparoxysmal responses (PPRs) through electroencephalography (EEG) recordings. IPS is used to investigate the flash frequency thresholds—both upper and lower—that trigger PPRs in individuals with suspected photosensitive epilepsy. This technique helps in diagnosing and understanding the neurological response to light stimuli, providing valuable insights for clinical research and patient assessment.

Polysomnography (PSG)

With polysomnography (PSG), a panel of physiological parameters is recorded continuously throughout the night in order to measure sleep objectively. PSG generally includes EEG, electrooculography (EOG), electromyography (EMG), electrocardiography (ECG), and respiration measurements.

Advanced EEG analysis

In our pursuit of excellence in biomarker engineering and analytics, we have identified a groundbreaking opportunity to extract and present a wealth of untapped information from EEG data. Recognising that standard reports capture only a fraction of the potential insights, we have developed an advanced processing pipeline to delve deeper into EEG analysis.

Our Biomarker Engineering and Analytics (BEA) team has validated a sophisticated processing pipeline that includes enhanced data cleaning and additional analytical steps. This innovative approach delivers significant added value, providing clients with deeper insights into drug-induced changes in whole-brain activity.

We present the additional information in an accessible format, featuring clear graphics that illustrate the effects of investigational compounds on brain activity at various doses and timepoints relative to dosing. For instance, our detailed graphs can quickly demonstrate how different frequency bands, such as theta, beta, and gamma waves, change over time or with increased dosage. A compelling visualisation might show increased theta wave activity during the first few hours post-administration compared to placebo, which then normalises after five hours. Such insights are invaluable for clinical scientists when making decisions about further clinical development.

In addition to enhanced cleaning and visualisations, the BEA team has implemented a cluster-based permutation analysis combined with linear mixed-effects models, allowing statistical analyses on each band of interest. They are also expanding this analysis to highlight significant changes in clusters of electrodes and frequencies due to drug effects, going beyond predefined frequency bands such as alpha and beta.